The objectives of the proposed project are: 1. To maintain and to develop the LOU rat system in order to help the research on the IgE physiology. 2. To study the induction and the regulation of the IgE synthesis, especially 1) role of the IgD membrane receptors in the precursors of the reaginic (IgE) antibodies synthetising cells. 2) genetic control of the reaginic (IgE) response. 3) regulation of the reaginic (IgE) response, especially after oral administration of the antigen. 3 To work in collaboration on different fields of the immunity in parasitic diseases. 1) with Pr D.D. McGregor, New York State College of Veterinary Medicine, Cornell University, USA, on immunity to Trichinella spiralis. 2) with Dr. E.E.E. Jarrett, University of Glasgow, on immunity to Nippostrongylus brasiliensis. 3) with Pr. A. Capron, University of Lille, on immunity to Schistosoma mansoni.